Check valves may be used in any one of numerous circumstances in which air flow may need to be regulated. One particular type of check valve is a split flapper check valve that includes a valve housing and a valve assembly. The valve housing defines a flow passage, and the valve assembly is disposed within the flow passage and is secured to the valve housing. The valve assembly includes a valve body having an opening, a hinge pin that extends across the opening, two valve flappers rotationally mounted on the hinge pin, and a stop tube that also extends across the opening. When airflow impinges on an upstream side of the valve flappers, one or both of the valve flappers unseat from the valve body to allow air to flow through the flow passage. In the full-open positions, the valve flappers engage the stop tube.
The above-described split flapper check valve is assembled by mounting the flappers on the hinge pin, and securing the hinge pin to the valve body via a clearance fit. The stop tube may also be secured to the valve body via a clearance fit. The valve body is then coupled to the valve housing using the two rivets. This assembly procedure can be tedious and time-consuming, which increases overall costs.
The above-described split flapper check valve can also exhibit leakage and wear issues. In particular, leakage may occur between the hinge pin and the valve housing, and between the valve body and the valve housing. The flappers are not highly loaded when the valve is open. As a result, the valve flappers may be vulnerable to motion and wear due to vibration and aerodynamic flutter. This can result in early field issues, warranty costs, and customer dissatisfaction. Moreover, the hinge pin may rotate, which can cause it to wear. In the full-open position, the flappers contact the stop tube, which can also cause wear.
Hence, there is a need for a split flapper check valve that does not exhibit the leakage and wear issues of presently known check valves, such as the wear issues at the hinge and the contact location between the flapper and any associated stop, and that does not rely on a relatively tedious, time-consuming, and thus costly assembly procedure. The present invention addresses at least these needs.